Plate 1 figs. a–h · 8 separate observations
Every figure is a research-grade observation under CC0, CC BY or CC BY-SA, rehosted with the photographer’s name, the licence and the observation it came from. Photographs under a NonCommercial licence are excluded from this site and are never stored, which costs us a great many pictures and is not negotiable.
The specimen a real sheet, in a real collection
- Herbarium
- The New York Botanical Garden
- Accession
- 307458
- Filed as
- Najas flexilis var. fusiformis Chapm.
- Det. by
- R. R. Haynes; W. A. Wentz 1974-01-01
- Collected
- A. W. Chapman
- Origin
- US
- The sheet
- View the digitised specimen (CC BY 4.0)
A real pressed plant, in a real collection, under the accession number above. Not an illustration of one. The holding institution does not serve this sheet’s image to third parties, so there is no photograph here. The record is real and the link goes to it. Where we hold no openly licensed sheet for a species this section is simply absent, and where a sheet never recorded who determined it, that field stays empty rather than being filled in. Roughly half of all herbarium sheets never recorded a determiner, which is ordinary.
Native range 68 botanical countries
Not drawn on the map: Great Britain. We hold no public-domain boundary for this region, so it is listed rather than guessed at.
Region boundaries approximated from Natural Earth (public domain) and mapped to TDWG World Geographical Scheme for Recording Plant Distributions (WGSRPD) level-3 botanical countries (Brummitt 2001). Indicative, not the official WGSRPD geometry.
Where it actually grows measured, from 214 observations
| Condition | 5th percentile | Median | 95th percentile |
|---|---|---|---|
| Coldest month, mean daily low | -17.9 °C | -12.9 °C | -6.4 °C |
| Warmest month, mean daily high | 21.7 °C | 24.0 °C | 27.3 °C |
| Annual rainfall | 386 mm | 907 mm | 1,298 mm |
| Rainfall in the driest quarter | 41 mm | 155 mm | 260 mm |
It is found where winters are severely cold. This is not care advice and it is not a forecast. It is a measurement: we sampled the climate at every one of the 214 research-grade observations of Najas flexilis that carry a coordinate, and this is the range those places actually span. The 5th and 95th percentiles are used rather than the minimum and maximum, because a single cultivated specimen in a heated conservatory should not widen a tropical plant's range to the Arctic.
This is not a hardiness zone. A USDA zone is the average annual extreme minimum temperature. The figure above is the mean daily minimum of the coldest month, which is a different quantity and is typically far warmer. Reading one as the other would place a plant several zones too warm, so we do not publish a hardiness zone, because we do not have one.
Also published as 9 synonyms
A synonym is not an error. It is a record of botanists disagreeing, in print, about where this plant belongs. Each of these was somebody’s considered answer.
- Caulinia flexilis Willd.
- Fluvialis flexilis (Willd.) Pers.
- Najas caespitosa (Maguire) Reveal
- Najas caespitosus (Maguire) Reveal
- Najas flexilis f. microcarpa (Nilsson) Neuman
- Najas flexilis subsp. caespitosa Maguire
- Najas flexilis var. congesta Farw.
- Najas flexilis var. microcarpa Nilsson
- Najas flexilis var. robusta Morong
Sourcesevery claim on this page
- World Flora Online Plant List. accepted name, authority, classification. CC0. Retrieved 2026-07-12.
- iNaturalist. photographs and flowering annotations, CC0 / CC BY / CC BY-SA only. per photograph. Retrieved 2026-06-27.
- Wikidata. common name (P1843), joined on the World Flora Online identifier (P7715). CC0. Retrieved 2026-07-13.
- Kew, World Checklist of Vascular Plants (WCVP v16). native distribution by TDWG level-3 botanical country, and life form. CC BY 3.0. Retrieved 2026-06-04.
We publish what we can source and we say so when we cannot. This page has no care advice and no toxicity claim, because we do not yet have those from a source we can cite.